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US 2004/0168991 A1Published application
Method and apparatus for clarifying and/or thickening a slurry
AssigneeOutokumpu Oyj
InventorsBror Nyman, Matti Nuorala
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AssigneeOutokumpu Oyj
InventorsBror Nyman, Matti Nuorala
Estimating the term…
The invention relates to a method of clarifying and/or thickening a solution containing solids i.e. a slurry, and the apparatus for accomplishing this. Using the method and apparatus of the present invention, the slurry to be fed into the clarification or thickening apparatus is distributed evenly into the slurry already in the tank. It is characteristic of the clarification tank now developed that the displacement capacity of the raking system in the tank is the same from the edges of the tank up to the centre. The displacement capacity is measured as being the same as the underflow discharge capacity from the centre of the tank. The displacement capacity can be determined to be the same using rake displacement plates of different heights, according to the distance of the displacement plates from the rake shaft and the number of plates rotating on the same ring-like cross-section.
A method for clarifying and/or thickening a solution containing solids, whereby the slurry is fed via a feedwell into a settling space for clarification, from whence the settled solids or underflow is removed via a discharge port in the centre of the settling space and the clarified solution or overflow is removed as an overflow, and where there is a rake in the settling space rotating on its shaft for displacing the underflow from the edges of the space towards the centre, with displacement elements on said rake radially to the tank, wherein the displacement element displacement plates at the same distance from the shaft move the underflow as they rotate from a ring-shaped cross-section towards the centre, characterised in that the displacement capacity of the underflow displacement elements on concentric ring-like cross-sections is basically the same from the edges of the settling space to the central area and the displacement capacity on the innermost concentric ring-like cross-sections of the central area is smaller than on the other cross-sections.
An apparatus for clarifying and/or thickening a solids-containing solution, whereby the apparatus comprises a clarification and/or settling tank (1), which is equipped with a feedwell (2) for the slurry to be settled, discharge ports (9) for the settled solids or underflow in the centre of the settling space, a discharge launder (16) for the clarified solution or overflow, and a rake (10) rotating on its shaft (11), which moves the underflow from the edges of the tank to the centre, where said rake has at least two arms (12) reaching the edge of the tank in a radial direction, characterised in that, in order to keep the underflow displacement capacity constant from the edges of the clarification and/or thickening tank (1) to the centre, there are displacement plates (13) attached to the rake arms (12,17), with a height dependent on the distance of the displacement plate from the rake shaft (11) and the number of rake arms, and the height of the displacement plates (13) in the central area (8), which is ring-like in shape and reaches from the rake shaft (11) outwards for a distance of 15-30% of the length of the long rake arms (12), is kept basically the same.
Dependencies are inferred from the claim text.